Coeliac disease occurs when people cannot tolerate gluten, which is found in such foods as wheat, barley and rye. Most coeliac disease patients can safely eat very small amounts of gluten. It is therefore widely accepted that gluten-free refers to a level of gluten that is harmless rather than to total absence. coeliac disease is not the same as food allergy to wheat. People with food allergy to wheat may not tolerate gluten-free food, as they may react to other allergens than gluten, and/or to lower amounts of gluten.
Coeliac disease is a disease of the small intestine triggered by ingestion of gluten. Gluten is a group of proteins found in foods such as wheat, barley and rye. When a person with coeliac disease ingests gluten an immunological reaction in the small intestine leads to flattening of the mucosa. We absorb most nutrients, vitamins and minerals in the small intestine. A flattened mucosa is not able to absorb nutrients, vitamins, and minerals very well and leads to many of the symptoms of coeliac disease, such as diarrhoea, weight loss, general weakness, anaemia, dementia, and osteoporosis.
It is estimated that about 1% of the population have coeliac disease and it is therefore an important public health issue. As a consequence of glutens causative in coeliac disease, the Codex Alimentarius Commission Committee on Food Labelling has listed wheat and other gluten-containing cereals on their list of the foods and ingredients known to cause hypersensitivity. The labelling legislation in Europe defines cereals containing gluten as wheat, rye, barley, oats, spelt, kamut or their hybridized strains.
Wheat can also trigger IgE-mediated food allergy. That is not as common as coeliac disease. More information on IgE-mediated wheat allergy can be found in the InformAll Database.
A life-long gluten-free diet is the only treatment for coeliac disease. Products with wheat, rye and barley must for example be avoided. Most patients tolerate products with oats as long as they are free from cross-contamination with other cereals containing gluten. On a gluten-free diet the flattened mucosa in the small intestine of coeliac patients heals and the symptoms disappear.
A recent scientific review of relevant studies concluded that most coeliac disease patients can safely eat somewhere between 10 and 100 mg gluten daily. For coeliac disease it is widely accepted that gluten-free refers to a level of gluten that is harmless rather than to total absence. The Codex Alimentarius Commission has recently reviewed the standard for gluten-free foods. In the revised standard they recommend the use of two categories
a) Gluten-free food with gluten content not exceeding 20 mg/kg
b) Gluten-reduced food with gluten content between 20 and 100 mg/kg.
People with an IgE-mediated food allergy to wheat may not tolerate gluten-free food, as they may react to other allergens than gluten, and/or to lower amounts of gluten than defined in the Codex standard.
Non-IgE-mediated and IgE-mediated food allergy:
The Codex recommendations:
The InformAll Database:
- Hischenhuber et al. (2006). “Review article: safe amounts of gluten for patients with wheat allergy or coeliac disease.” Aliment Pharmacol Ther 23, 559-575.